Centerless grinding machine



March 18, 1947. c w op ms 2,417,413

CENTERLESS GRINDING MACHINE Filed Jan. 5, 1945 2 i t 1 March 18, 1947.c, w, HO s 2,417,413

CENTERLESS GRINDING MACHINE Filed Jan. 5, 1945 2 Sheets-Sheet 2 ril .I

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Patented Mar. 18, 1947 2,417,413 CENTERLESS GRINDING MACHINE Cecil W.Hopkins, Waynesboro, Pa., assignor to Landis Machine Company,Waynesboro, Pa., a corporation of Pennsylvania Application January 5,1945, Serial No. 571,518

8 Claims.

This invention relates to grinding machines of the centerless type inwhich the work piece is supported on a plate or work rest verticallymounted between the opposed peripheral surfaces of a grinding wheel anda control or regulating wheel. In such machines, the work piece isrotated upon the work rest and simultaneously forced against theperipheral face of the grinding wheel by the control wheel. Machines ofthis general type are shown in United States Patents Nos. 2,091,655 and2,346,851.

The present invention relates more particularly to importantimprovements in the mounting and adjusting means for the work rest andthe work locating and lead controlling device shown in the co-pendinapplications of Arthur Scrivener, Serial No. 556,426, filed September29, 1944, and Cecil W. Hopkins and Edwin M. Eigenbrode, Serial No.557,128, filed October 4, 1944.

In the machines disclosed in the pending ap-' plications, designedprincipally for the grinding of cylindrical surfaces, the work restplate is mounted upon an adjusting slide for the control wheel head andis supported at opposite side of the grinding and control wheels by twoindependently adjustable brackets for the purpose of positioning thework supporting surface of the work rest with respect to the axis of thegrinding wheel. By reason of the independent vertical adjustment of theopposite ends of the work rest, certain inaccuracies in the propersetting of the work rest are inevitable. However, these are notobjectionable in ordinary cylindrical grinding wherein the work restplate is usually inclined relative to the grinding wheel axis so thatthe action of the control wheel and grinding wheel on the work willoperate to move the work piece progressively during the grindingoperation from between the opposed surfaces of the wheels. In such case,the degree of inclination of the work rest surface aflects only the rateof axial movement of the work-piece, which need not be accurate.

On the other hand, in machines intended primarily for the grinding ofscrew threads and other hel cal surfaces, the work rest plate must beinclined with respect to the axis of the grinding wheel by an amountequal to the helix angle of the thread being ground. As this settingmust be made with some exactness, the independent adjustment of the workrest plate at its opposite ends. as shown in the above-identifiedpending applications, is not satisfactory, since the proper setting oradjustment of the work rest by such trial and error methods is laboriousand timeconsuming.

Accordingly, it is the principal object of the present invention toprovide means for facilitating the easy, quick and accurate adjustmentof the work rest to position the work supporting surface thereof at arequired definite inclination relative to the axis of the grindingwheel.

It is also another object of the invention to provide an oscillatablecradle for the work rest with means to releasably secure the same in afixed adjusted position, and means for adjustably mountin the work reston said cradle so that the work-piece will be supported slightly abovethe center of oscillation of the cradle, re-

gardless of the diameter of the work-piece.

A further object resides in the provision of a work locating and leadcontrolling device, mounted on the work rest cradle and simultaneouslyadjustable therewith relative to the grinding wheel axis.

It is also an additional object of this invention to provide a worklocating device pivotally mounted on one end of the work rest cradle andembodying a lead controlling finger, together with means resistingpivotal movement of said device in one direction and yieldingly holdingsaid finger in engagement with the work.

It is a still further object of my invention to provide a simple,unitary assembly of the work rest cradle and work locating and leadcontroL. ling device which will materially expedite quantity productionof accurately finished work-pieces by obviating the time-consuming trialand error method of adjusting or setting the work rest and theindependent setting or adjustment of the work locating and leadcontrolling finger with respect to the work-piece.

In general, the present invention comprehends a novel adjusting meansfor the work rest and the work locating means as above characterized,which comprises a very compact assembly of a minimum number ofstructurally simple cooperating elements which will be highly eflicientin their functional operation, as well as rugged and durable inpractical use.

With the foregoing and other subordinate objects in view, the inventioncomprises the improved centerless grinding machine and the constructionand relative arrangement of the several parts as will hereinafter bemore fully described, illustrated in the accompanying drawings, andsubsequently incorporated in the subjoined claims.

In the drawings, wherein like reference characters designatecorresponding parts throughout the several views and in which I havedisclosed one simple and practical embodiment of the invention:

Figure 1 is a side elevation showing one concrete example of my improvedadjustable work rest and work locating mechanism, certain parts thereofbeing shown in section as indicated by the line ll in Figure 5.

Figure 2 is a vertical sectional view taken substantially on the line2-2 of Figure 1. I

Figure 3 is a fragmentary sectional view take substantially on the line-33 of Figure 1.

Figure 4 is a fragmentary side elevation, partly in section, asindicated by the line 4--4 in Figure 5, and

Figure 5 is an end view showing the mounting of the work locatingmechanism and being partly in section, as indicated by the line 5-5 inFig- .ure 1.

Referring in further detail to the drawings in Figures 1 and 2 thereof,I have shown a portion of the main slide l6 upon which my imtrol wheell6 journalled therein for adjustment relative to the work rest. Anyconventional means may be provided for adjusting the main slide l0whereby the work rest mounted thereon together with the control wheelmay be adjusted as a unit relative to the periphery of the grindingwheel l8. In the present instance the peripheral face of this grindingwheel is formed with alternating V-shaped ridges and grooves indicatedat for the grinding of screw threads;

In the illustrated embodiment of my invention, I provide a base 22having alongitudinally extending rib 24 on its bottom face adapted to beseated in a transverse groove or channel 26 on the upper surface of theslide [0. The base 22 is provided with a plurality of counterboredvertical openings 28 to receive the headed attaching screws 30 adaptedfor engagement in threaded bores 32 in the end of slide "I, whereby saidbase is rigidly secured to the slide. The upper surface of the base 22is formed with an arcuately concave seat 34 for the work rest cradle 36having a complementary convex bottom surface for sliding contact withsaid seat. A concentric dovetail rib 38 is formed upon the bottomsurface of the cradle and is adapted for engagement in a groove 40formed in the upper surface of the base 22. This groove angles to thebase of the groove, as at 42, while the opposite sidewall of said grooveis upwardly and inwardly inclined from the base thereof to provide anoverhanging V-shaped lip 44 with which one side edge face of thedovetail rib 38 on the cradle 36 is adapted to contact.

While various means might be employed for adjustably and detachablyclamping the work rest cradle 36 ,on the base 22, in Figure 3 of thedrawings I have shown one simple and efiective means for this purpose.Preferably, at the side of the groove 40 having the vertical edge wall42, transverse cylindrical openings 46 are formed in the base 22 and attheir inner ends communicate, at the upper sides of said openings, withthe groove 46. In spaced relation to each of said openings and in axialalignment therewith, the base is provided with a threaded bore 48. Ineach of the openings 46a cylindrical clamping member 50 is engaged andis provided at the upper side thereof with an undercut recess 62 toreceive the opposed edge portion of the rib 36 on the cradle 36. Themember 56 is further formed with an'axial opening 54 counterbored atits\ outer end to receive the head of a clamping screw 56 looselymounted in said opening. The screw headis provided with suitable meansfor the application of a wrench thereto and when the threaded shank ofthe screw is adjusted in the threaded bore 48, the member 50 is forcedinwardly into clamping engagement with one side of the rib 38 on thecradle 36 and urges the said cradle transversely upon the seat 34 toforce the opposite side edge of said rib into tight clamping engagementagainst the lip 44 on the base 22.

Above the rib 38 a laterally projecting flange 58 is formed on one sideof the cradle 36, the vertical edge surface of this flange being flushwith the adjacent side face of the base 22. Upon said side face of theflange 58, at a suitable location, a degree scale 60 is engraved, theindividual lines of said scale being substantially radial with respectto the center of the semicylindrical surface of the cradle 36 andcoact-- ing with an index line 61 provided on the side face of the base22. It will, therefore, be understood that the amount of angulardisplacement of the cradle 36 with respect to the base 22 from its meanor neutral position may be directly read in degrees on the scale 60. Thecenter of oscillation of the cradle is accurately located in the samehorizontal plane as the axis of the grinding wheel l8.

As shown in Figure 2 of the drawings, the top of the cradle 36 is formedwith a longitudinally extending groove 62 of rectangular form which isadapted to receive any one of a plurality of metal spacing strips -64 ofa selected thickness. The groove 62 is of such depth that the strip 64will occupy only a portion thereof, said groove above the spacing stripreceiving the lower edge portion of the work rest plate 66. The oppositeend portions of the cradle 36 extend for approximately the same distanceon opposite sides of the control wheel l6 and grinding wheel 18 and areeach formed with an upwardly projecting bifurcated lug or extension 68,the space between the separated portions of said lug being substantiallyequal to the width of the groove 62, and in communication with onerendof said groove. In one side portion of each lug 6 8 one or more setscrews 10 are threaded for bearing contact with one side of the workrest plate 66 at each end thereof to force the plate into tight clampingengagement against the opposite side portion of the lug 68. Thus lateralshifting movement of the plate 66 relative to the supporting cradle 36is effectively prevented.

The work rest plate 60 is centrally formed with an upwardly extendingrelatively narrow portion 12, one side face of which, opposed to controlwheel I6, is formed with a bevelled or arcuate surface 14, providing arelatively thin upper portion of the plate extending between thecontiguous peripheral surfaces of the control wheel and grinding wheeland having a transversely bevelled or inclined work-receiving topsurface I6 extending downwardly from the periphery of the grinding wheell8 towards the control wheel l6. Thus the work-piece, indicated at W,will be properly supported by the work rest plate 66 for rotation by thecontrol wheel [6 against the peripheral grinding face of the wheel l8,in the manner described in the above-identified copending applications.

. As thus far described, it will be readily understood that by looseningthe clamping members 50, the cradle 36 may be angularly adjustedrelative to the base 22 to quickly and accurately position the workreceiving surface 16 of the plate 66 at a desired predeterminedinclination relative to the axis of the grinding wheel I8 so that therapidity of the progressive axial movement of the work-piece in thegrinding operation may bevaried as described.

For the purpose of accurate finish grinding of a work-piece having aroughly pre-formed thread, I provide the cradle 36 with a detachableunit to properly locate the thread with relation to the grooves in theperipheral face of the grinding wheel I8 and to control the lead oraxial movement of the threaded workpiece. This work locating and leadcontrolling unit will now be described with more particular reference toFigures 1, 4 and 5 of the drawing.

As shown in Figure 1, one vertical end face of the cradle 36 is providedwith a horizontal rectangular groove 18. This groove receives a rib 82of similar form provided upon one side face of the base of a bracketmember 80. This bracket is further rigidly secured to the end of thecradle 36 by a plurality of screws 84'. The base of the bracket 80 atone side edge thereof is formed with an angularly disposed upwardlyextending arm 84, the lower end of this arm being provided with a lug 86extending inwardly therefrom in spaced parallel relation to the base ofthe bracket. In this lug an adjustable stop pin 88 is threaded andlocked in adjusted position by means of the nut 90. The purpose of thisstop pin will be presently explained.

In an opening provided in the upper end of the arm 84 one end of a studshaft 92 is rigidly fixed. preferably by means of the set screw 94having a conical inner end coaeting with shaft 92 to urge said shaftaxially and tightly hold one side face of the enlarged cylindricalsection 86 of said shaft in abutting contact against the inner side faceof the arm 84.

Upon the shaft 92 a bracket 98 is fulcrumed intermediate of its ends forrocking movement in a plane parallel with the plane of the work restplate 66. I preferably journal this bracket upon the shaft 92 by meansof the anti-friction bearings I00 disposed within opposite ends of theopening I02 in said bracket and having inner and outer race rings spacedapart by means of the annular spacing sleeves or bushings I04. The innerrace ring of one of these hearings abuts against the shoulder formed bythe shaft section 96 and the bearings are retained in properly assembledposition on the shaft 92 by means of the washer I06 engaged with theouter side of the other of said bearings and the nut I08 engaged uponthe threaded end IIO of the shaft 92. A hollow cap member I I2 issecured to the bracket by the screws H4 and is formed with a flange I I6extending into the opening I02 in abutting contact with the outer facering of the adjacent bearing.

0A suitable grade of lubricant is supplied to bearings I00 and isretained therein by means of a conventional grease seal II8 frictionallyfitted within the opening of an annular cap plate I20 fixed to thebracket member 98 by means of screws I22. This cap plate also has anarrow annular flange I24 extending within the end of the opening I02and abutting against the outer race of the adjacent bearing I00. It willbe noted that the cap plate I20 is spaced from the adjacent side face ofthe arm 84 so that freedom of oscillating or rocking motion of thebracket 88 upon the shaft 92 is assured.

The bracket 88 at its lower end is formed with a horizontally elongatedcylindrical portion I26 at right angles to the fulcrum axis of thebracket and having a cylindrical bore I28. In this bore a sleeve I30 isfitted, said sleeve having a closed outer end I32 projecting from saidbore and having bearing contact against the boss I34 formed upon thebase of the bracket 80. A spring I36 bears at one of its ends againstthe closed end of the sleeve I30 and at its other end is seated againstthe plug I38 slidably disposed within the inner end of the bore I28. Anadjustable screw I40 threaded in the end of the bracket extension I26and bearing against the plug I38 regulates the pressure of the springI36 against said plug, tending to rock the bracket 98 in a clockwisedirection on the said shaft 92 from the position seen in Figure 1 of thedrawing. Movement of said bracket member in the counter-clockwisedirection to its normal position is limited by contact of the dependinglug I42 on the bracket with the adjustable stop 'pin 88. The screw I40is locked in adjusted position by means of the nut I44 contacting theend face of extension I26 of the bracket 98.

The bracket 98 is also formed at its upper end with a horizontallyelongated extension I46 having a. cylindrical bore I48. The bore I48opens through the extension I46 adjacent to the grinding wheel I8 andfrom this open end of the bore the member I50 extends between thecontrol wheel and the grinding wheel. The opposite end of the bore I48is closed by means of the plate I52 secured to the end of the bracketextension I46 by means of screws I54. This plate has a central openingthrough which a rod I60 extends, said rod being threaded at its innerend, as at I58, for threaded engagement in an internal threaded sectionI60 of the tubular member I50. To the outer end of the rod I56a'suitable turning knob I62 is fixed whereby said rod may be rotated tolongitudinally adjust the position of the member I50 within the boreI48. A coiled spring I64 surrounds the rod I56 within the bore I48 andbears at one of its ends against plate I62 and at its other end againstthe base wall of the spring receiving socket I66 formed in the end ofthe member I50. Thus by turning the rod I56 to longitudinally adjust themember I50 the spring I64 is placed under compression and tends to urgethe member I50 from the open end of said bore. Rotative movement of themember I50 within the bore I48 is prevented by means of a suitable keyI68 fixed to the end of the extension I46 by the screw I10 and engagedin the external key-way I12 formed in the wall of the member I50.

Referring particularly to Figure 5 of the drawings, it will be notedthat above the member I50 bracket extension I46 is formed with atransverse opening I14, the lower side of which intersects the upperside of the bore I 48. Cylindrical members I56 are fitted into theopposite ends of said bore. Each of these members is of tubular form andthe wall of one member is internally threaded as at "8 while the othermember is counterbored to receive a-headed adjusting screw I80. Theopposing ends of the members I56 at their lower sides are provided withbevelled surfaces I82 substantially tangent to the peripheral surface ofthe member I50. It will thus be understood that, by adjusting the screwI in the threaded end I18 of the member I16, the opposbe set.

' The lower extremity of this fingerhas oppositely bevelled side facesproviding an edge I86 dis- 1 posed transversely of the work receivingand'supporting surface I6 of the work rest plate .66 and adapted forengagement in the trough or groove of the thread on the work-piece W.The work locating finger -I84 is held in its adjusted position againstvertical or rotative movement relative to the member I58 by means of thecylindrical plug I88 in the bore of member I68 urged into frictionalclamping contact against one sideof the finger I84 by means of theadjustablescrew I98 threaded into the end of the bore in the member I58.

It is obvious that by adjusting the work rest cradle 36upon the base. 22in the manner above described, the work receiving and supporting surface16 of the plate 66 may be disposed at the required angle from thehorizontal in consonance with the helix angle of the thread to beground. The work locating and lead controlling finger I84 is firstadjusted axially of the grinding wheel I8 and set in proper relationshipwith the thread receiving grooves of the peripheral surface of saidwheel in the manner above explained. The controlwheel I6 is providedwith circumferentially spaced peripheral work receiving and dischargingpockets I92 as in the co-pending application above referred to. Thus inthe oscillation of the control wheel the work-piece will be fed from oneof said pockets upwardly over the surface 14 of plate 66 and upon thework receiving and supporting surface I6 where it is guided into properrelationship with the grooved face of the grinding wheel I8 by thefinger I84. During the entire grinding operation, the lower end of thisfinger is in contact with the roughly formed thread of the work-pieceand thus controls the lead of the thread being ground. In the adjustmentof the work rest cradle 36 on the base 22, the work locating unit is, ofcourse, also adjusted as a unit therewith so that the operation of thelocatin and lead controlling device will be the same regardless of theangle at which the cradle 36 may The spring I36 acts to yieldingly urgethe lower end of the finger I84 into contact with the work, and byproperly adjusting the stop pin 88, the movement of the bracket member98 in the mounter-clockwise direction in opposition to the spring I36determines the position of the lower edge I88 of the finger I84 withrespect to the threads.

It will be noted that the vertical position of the work supportingsurface 16 of the plate 66 with respect to the cradle 36 is determinedby the diameter of the particular workpiece and it can be accuratelyfixed by the use of the spacing strips 64 of various thicknesses so thatthe workpiece will be supported upon said surface some what above thecenter of oscillation of the cradle when the work-piece is parallel tothe axis of the grinding wheel I 8, as shown in Figure 1 of thedrawings. Therefore, for work-pieces of large diameters, thin spacingstrips 64 will be used while for small diameter workpiecesrelativelythick spacing strips will be employed. Thus, the selection ofthe proper spacing strip determines the position of the work rest bladein the cradle and remains the same with respect to a. verticalplaneintersecting the center ofoscillation of the cradle in all-angularadjustments of the latter.

In certain types of grinding machines, the shaft. of the control wheelI6 is mounted at its approximate geometrical center for pivotal movementin a vertical plane so that it may be set at a desired 'angle withrespect to the axis of the grinding wheel. In the application and use ofthe present invention in connection with this type of grinding machine,the center of rocking motion of the cradle 36 is located in accuratehorizontal alignment with the pivotal center-of the control wheel shaft,as well as the axis of the grinding wheel, thus insuring that the worksupporting surface I6 and the work-piece thereon can always bedisposedin accurate parallel relation with the axis of the control wheel I6.This requirement is essential to the accurate grinding of a trulycylindrical surface of uniform diameter.

In the grinding of certain-kinds of work, the use of the work locatingand lead controlling unit may not be required. In such a case, it can bereadily detached'from the end of the cradle 36 by merely removing thescrews 84'. Also when it is desired to remove the cradle 36 from thebase 22, this may be readily accomplished by simply removing the members58 so that the dovetail rib 38 on the cradle can be moved upwardly outof the groove 48 in the base'22.

From the foregoing description it is believed .that the construction,manner of use and several practical advantages of the present inventionmay be readily understood. It will be seen that I have devised a novelwork rest supporting and adjusting means for centerless grindingmachines which obviates the laborious and time-consuming operationsinvolved in the making of separate adjustment of the work rest atopposite ends thereof. It will also be evident that the presentinvention is particularly advantageous for the high precision grindingof such work-pieces as threaded rods or bolts, where the pitch, helixangle and concentricity of the screw threads is of major importance. Bymounting the work locating unit directly upon the supporting cradle forthe work rest plate, the necessity of making a separate adjustment ofthe work locating finger for each adjustment or setting of said restsupport is eliminated. In addition it will be seen that the presentinvention comprises a comparatively small,

number of elements which are of simple and durable structural form,capable of expeditious and accurate assembly, and will function in aneflicient and reliable manner to accomplish the purposes in view.

The invention may be embodied in other specific forms without departingfrom the spiritor essential characteristics thereof. The presentembodiment is therefore to be considered in all respects as illustrativeand not restrictive, the scope of the invention being indicated by theappended claims rather than by the foregoing description, and allchanges which come within the meaning and range of equivalency of theclaims are therefore intendedto be embraced therein.

What is claimed and desired to be secured by United States LettersPatent is:

centerless grinding machines, comprising a work rest plate, a supportfor said plate, means for angularly adjusting said support to positionthe work receiving surface of said plate relative to the grinding wheelaxis, a device mounted upon said support for movement with and relativethereto and having a finger disposed in angular relation to the path ofmovement of said device on the support to engage the periphery of thework piece and locate the work piece on the work rest plate with respectto the face of the grinding wheel, and means coacting with said deviceto yieldingly urge the same in one direction relative to the support andhold said finger in contact with the work-piece.

2. The combination defined in claim 1, in which said device is pivotallymounted on one end of the support.

3. The combination defined in claim 1, in which said device include abracket pivotally mounted intermediate of its ends on the support, andsaid work locating finger is mounted on one end of said bracket,together with spring means coacting with the other end of the bracket toyieldingly hold said finger in contact with the work-piece.

4. The combination defined in claim 1, in which said device includes abracket pivotally mounted intermediate of its ends on the support,together with means on one end of said bracket for adjustablypositioning the work locating finger with respect to the pivotal axis ofthe bracket, and spring means coacting with the other end of the bracketto yieldingly hold said finger in contact with the work-piece.

5. Work rest supporting and adjusting means for centerless grindingmachines comprising a cradle for a work rest, means for oscillatablymounting said cradle for angular adjustment about a fixed axis, meansfor releasably retaining said cradle in adjusted position, a worklocating device mounted on said cradle for adjustment as a unittherewith, and means for angularly adjusting the position of said devicerelative to the cradle.

6. The combination defined in claim 5, in which said work locatingdevice includes a work engaging finger vertically movable above thecradle, together with spring means yieldingly urging said finger intocontact with the work piece.

7. The combination defined in claim 5, in which said work locatingdevice is pivotally mounted on the cradle.

8. Work rest adjusting and supporting means for centerless grindingmachines comprising a base having a concave upper surface and aconcentric groove therein formed with an undercut side wall, a work restsupporting cradle having a convex surface slidable on said concavesurface and provided with a dovetail rib removably engaged in saidgroove, and clamping means securing the cradle in adjusted position onthe base including a member transversely movable in the base andcoacting with one side edge of said rib to transversely shift the cradleon the base and urge the opposite edge wall of said rib into clampingengagement with the undercut side wall of said groove.

CECIL W. HOPKINS.

REFERENCE S CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,709,348 Helm Apr. 16, 19291,639,958 Norton Aug. 23, 1927 1,983,853 Hopkins Dec. 11, 1934 2,091.655Scrivener Aug. 31, 1937 FOREIGN PATENTS Number Country Date 247,037British Feb. 11, 1926 248,893 British Mar. 18, 1926

